Looking for logging into the Jenkins Page Message site and are not getting the correct working link for it? In such a case, you can use the links given here by searching your desired login page in the search box. If the page is present on our website then you will get all the links related to the Jenkins Page Message site. After that you can login as usual with your login credentials.
https://wiki.jenkins.io/display/JENKINS/Login+Theme+Plugin
https://jenkins.io/blog/2018/06/27/new-login-page/
https://issues.jenkins-ci.org/browse/JENKINS-18439
https://stackoverflow.com/questions/31828839/how-can-i-change-edit-jenkins-default-message-on-login
https://groups.google.com/d/topic/jenkinsci-users/v8GxcZtfq60
https://gist.github.com/gustavohenrique/7465087
https://github.com/jenkinsci/login-theme-plugin
https://support.cloudbees.com/hc/en-us/articles/218348277-How-to-apply-custom-styling-to-my-instance-
https://devopscube.com/setup-custom-materialized-ui-theme-jenkins/
https://www.jetbrains.com/help/youtrack/incloud/map-project-to-jenkins.html
https://www.oreilly.com/library/view/jenkins-the-definitive/9781449311155/ch04s03.html
https://superuser.com/questions/879392/how-force-jenkins-to-show-ui-always-in-english
https://embeddedartistry.com/blog/2017/12/28/jenkins-generating-blue-ocean-urls